Underwater Turbines Help to Power the City that Never Sleeps

For as long as there have been cities, they have been moored by rivers.

With good reason: Historically, cities have needed fresh, moving water for all sorts of reasons – for drinking water, for transportation, for the moving of goods. Thus, around the world, we have pairings of great cities and rivers: Cairo and the Nile; Paris and the Seine; my beloved New York and its majestic Hudson and East Rivers.

These days, as the summer’s record heat slips away, I’ve been thinking a lot about rivers and cities and how, together, they hold some of the answers to the problem of global warming. In particular, I’ve been thinking about the East River, where a few weeks ago, an underwater turbine generating clean, renewable energy was yanked up from the river bottom for inspection. According to the New York Times, the turbine worked A-okay.

That’s good news for all of us, even if we don’t live in New York, because it and other recent advances in the field signal the growing potential of marine renewable energy. That’s what experts call energy generated from oceans and rivers in ways that don’t necessitate dams. (Dams can create a host of environmental problems by stopping rivers’ flow.)

The inspected turbine is part of a group of 30 that will be installed in the East River over the next five years by the innovators at Verdant Power. The project is the nation’s first licensed commercial tidal power project. And it is the brain child of a visionary energy pioneer, Trey Taylor, who has spent the last decade realizing his dream. Verdant’s idea is a smart one: use the incredible power of moving waters to generate electricity near the population centers that have sprung up around them over the centuries. That makes inherent sense. After all, such positioning can reduce the need for expensive transmission infrastructure and can help prevent the transmission losses that account for 7 percent of all US electricity.

Add to that this impressive fact: these turbines work both in rivers and in tidal environments. In rivers, the one-way flow of fast-moving water can provide a constant stream of reliable, baseline power. In tidal areas—New York City’s East River is actually a tidal channel—power output is as chartable as the phases of the moon.

Harnessing the energy of rivers, waves and flowing water in constructed canals is a burgeoning field, with scientists and engineers like those at Verdant creating a multitude of energy-capturing and transmitting devices. As my colleague Nathanael Greene has explained, the US Department of Energy estimates, based on a report by Georgia Tech, that tidal electric generation here in the U.S. could produce as much as 250 terrawatt hours of electricity a year, enough to power tens of millions of homes.

Equally impressive is that, with rigorous environmental review and careful siting, the field is finding ways to utilize this energy without hurting local ecosystems. Verdant’s environmental review studies have found that these devices and others like them move slowly, so marine animals don’t get hurt. And the water tends to be fast-flowing, meaning fish don’t hang around. I’ve been to Verdant’s control station on Roosevelt Island, where Verdant staff keep an eye on the underwater turbines and any interactions with fish and other wildlife. It’s an impressive monitoring operation, and one that Verdant will maintain as they install all thirty turbines over the next five years.

Within 20 years, devices like Verdant’s East River turbine could provide 5 percent of the nation’s electricity, says John Miller, who heads the New England Marine Renewable Energy Center at the University of Massachusetts. “It’s an aggressive but achievable goal.”

It’s one that befits New York City’s pioneering and innovative spirit. Verdant Power’s project further unites rivers and cities, with energy solutions that benefit us all.

EH, thanks for this comment and for your interest in tidal power and its environmental impacts. In response to your question, the Federal Energy Regulatory Commission (FERC), which is the federal agency which reviews marine power proposals, did prepare an environmental assessment of the Verdant project. It is summarized here: http://www.ferc.gov/media/news-releases/2012/2012-1/01-23-12-order.pdf. FERC concluded that Verdant project: "would not constitute a major federal action significantly affecting the quality of the
human environment. The project will be safe if operated and maintained in accordance
with the requirements of this license." Verdant also has a substantial environmental monitoring program underway so that it can ensure safe operation for wildlife.

Let's do a reality check on your (and Mr. Greene's) statement, "...tidal electric generation here in the U.S. could produce as much as 250 terrawatt hours of electricity a year, enough to power tens of millions of homes."
If you delve deeply into the Georgia Tech report, you find (Table 6) that 93 percent of the resource is in Alaska. Also (Pg. 26): "This upper bound on the available power ignores losses associated with turbine operation and assumes that turbines are deployed in uniform fences, with all the water passing through the turbines at each fence."

I'm thinking that it will be difficult to find "tens of millions of homes" in Alaska. I also suspect that killer whales and salmon might object to passing through turbines. (As would shipping through the entrance to the San Francisco harbor and many other areas where this resource exists.)

My point is that this story, and many others of a similar nature, lead the readers to think that we don't have to make any hard choices. All options need to consider scalability, practicality, economics and negative impacts. When you just extrapolate from Table 6, which is "total theoretical available power" you leave a false impression with your readers. The Georgia Tech report clearly stated the limitations, but they don't get into your blog.

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